[report] Support copying directories from containers

[pmoravec]

A minimalistic but efficient way of copying whole directory from a container. It does not work with "runas" where we call "cat", though.

Moreover:

• support add_forbidden_path on files collected from containers
• for content of directories copied from a container, let postproc to work on them

Resolves: #4190
Closes: #4191

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[packit-as-a-service]

Congratulations! One of the builds has completed. 🍾

You can install the built RPMs by following these steps:

• sudo dnf install -y 'dnf*-command(copr)'
• dnf copr enable packit/sosreport-sos-4191
• And now you can install the packages.

Please note that the RPMs should be used only in a testing environment.

[pmoravec]

Ideally, we should implement _expand_copy_spec within a container, to really properly and trully copy all copypaths "as is", e.g. respecting symlinks and following their destinations. With this approach, we get copied content of a symlink destination:

# podman exec foreman ls -l /usr/tmp
lrwxrwxrwx. 1 root root 10 Jun 25  2024 /usr/tmp -> ../var/tmp
# podman exec foreman ls -l /usr/tmp/
total 0
-rw-r--r--. 1 foreman foreman 0 Dec 21 11:32 touch
# 
# mkdir test_dir
# podman cp foreman:/usr/tmp test_dir
# file test_dir/tmp/
test_dir/tmp/: sticky, directory
# ls -l test_dir/tmp/
total 0
-rw-r--r--. 1 root root 0 Dec 21 12:32 touch
#

Our PR mimics this behaviour. Fully correct one would be to traverse the directory within the container (nontrivial in general) and iteratively copy individual files and/or symlinks and/or dirs - every copied piece would have to be prepped by podman exec "what file it is?".

Until there is a need of reliably copy symlinks within containers, that lengthy approach is not needed, imho.